E100: Tumor regression concordance between colon cancer primary and liver metastasis treated with neoadjuvant chemotherapy and simultaneous definitive resection

ePoster Abstract Author(s)

James D. McDonald, MD

Surgical Oncology Fellow
Moffitt Cancer Center, Florida, United States

Submitter(s)

James D. McDonald, MD

Surgical Oncology Fellow
Moffitt Cancer Center, Florida, United States

Author(s)

James D. McDonald, MD

Surgical Oncology Fellow
Moffitt Cancer Center, Florida, United States
AN

Afrin Naz, MD

Internal Medicine Resident
University of South Florida, United States
Jason W. Denbo, MD

GI/HPB Surgeon
Moffitt Cancer Center
Tampa, Florida, United States
DA

Daniel A. Anaya, MD, MSHCT

Head of GI Surgery
Moffitt Cancer Center, United States
AS

Amalia Stefanou, MD

Surgical Oncologist
Moffitt Cancer Center, Department of Gastrointestinal Oncology, United States
Seth I. Felder, MD

Colon and Rectum Surgeon
H. Lee Moffitt Cancer Center and Research Institute, United States

Introduction: Preoperative systemic chemotherapy is frequently administered prior to curative intent surgery in patients with resectable colon cancer with colon liver metastasis (CLM). Histologic response to preoperative chemotherapy in the CLM and primary colon tumor is frequent. However, the degree of viable tumor to fibrosis is variable and represents a standardized pathologic tumor regression grade (TRG) assessment. The concordance of TRG between the primary tumor and CLM exposed to the same systemic treatment is not well described. Additionally, it remains unknown how the primary and CLM TRG relationship influences recurrence.

Methods: A retrospective analysis of a prospectively maintained database of synchronous colon cancer and CLM patients receiving preoperative chemotherapy followed by combined resection at a single center was analyzed. Data were collected on pre-/post-operative clinicopathologic features. TRG was verified in the primary and metastatic lesions of all patients, and grouped into complete/near-complete response, partial response, and poor/no response. Concordance was determined by comparison of those groups.

Results: Twenty-eight patients were included in the analysis. The median age was 59 years, with an even gender distribution, and 75% of patients were Caucasian. Most patients (54%) had multiple CLMs and 93% received >4 cycles of preoperative chemotherapy. Over half of the primary tumors (57%) were in the ascending/transverse colon. Fourteen (50%) of the patients histologically demonstrated a TRG in the CLM of <3 with two showing a complete response. Tumor regression was present in the colon primary in 15 patients (53%). Sixty-four percent of patients had concordant responses in the primary tumor and CLM. Eighteen patients had experience recurrent disease with most (13 of 18,72%) recurring intra-hepatic. On univariate analysis, only primary tumor pathologic lymph node involvement was associated with TRG concordance (P = 0.02).

Conclusions: Histologic tumor regression concordance between a colon primary and synchronous CLMs exposed to the same course of systemic chemotherapy is common and more frequently seen in patients with primary tumor nodal involvement. The impact of TRG concordance and discordance on survival as well as patterns of recurrence, however, remains poorly described. When a perioperative chemotherapy strategy is planned for synchronous CLM, discordant TRG of the metastatic and primary tumor exposed to the same chemotherapy course may influence the postoperative treatment strategy.

Learning Objectives:

list factors impacting TRG concordance between primary and metastatic lesion.
define TRG concordance.
describe potential treatment alterations that might be impacted by discordant TRG findings.